A report by a group of experts, mandated by the United Nations Security Council to investigate on the situation in eastern Congo, has found that a vast international network that spans more than 25 countries is helping the Rwandan Hutu rebels of the Democratic Forces for the Liberation of Rwanda (FDLR) continue their atrocities in the region.

The U.N. report says the network of people, most of whom are living in Europe - but also in Africa, Asia, and the United States, is helping the rebels buy arms and transfer money in violation of a United Nations embargo against the FDLR.

A briefing on the report by the sanctions committee on Congo was due to be presented to the U.N. Security Council in a closed-door meeting on Wednesday. The briefing was postponed because of the sensitive evidence in the report against some member states said to be providing material support to the FDLR.

The report says a military operation launched by the Congolese Armed Forces (FARDC), with the backing of United Nations mission in the Congo (MONUC), has failed to rein in the rebels.

The report says the rebels have returned to most of the areas they had been chased from by the FARDC. They have also carried out reprisal attacks against the population.

Most of the FDLR rebels were involved in the Rwandan genocide in 1994 before fleeing to eastern Congo. They have since committed numerous atrocities against the Congolese population.

The report says the rebels continue to traffic mineral resources from the areas under their control, providing them millions of dollars to fund their operations. International mining companies are buying minerals from regional suppliers linked to the FDLR.

Tin ore giant Thailand Smelting and Refining Company (THAISARCO), a subsidiary of British metals group Amalgamated Metals Corporation (AMC), said in September it was suspending purchases from Congo.

Global Witness said in a press release on the U.N. findings on Wednesday that AMC and Malaysian Smelting Corporation (MSC) are “among the persistent offenders.” The group’s Campaigns Director Gavin Hayman said “They have been named time and time again in reports by the Group of Experts and Global Witness, yet continue to use suppliers and middlemen who buy from mines controlled by armed groups.”

The report also accused people, including government officials, in two neighboring countries, Tanzania and Burundi, of helping the FDLR. The UN experts say they have evidence of phone calls between these officials and elements of the FDLR. Burundi is also named as a rear base for the rebels.

Both countries denied the U.N. findings on Wednesday, while saying they would investigate.

The report says most of the people helping the FDLR are living freely in Europe. 21 phone numbers in France alone were found to be in regular contact with FDLR military satellite phones in 2008.

The U.N. experts say some attacks by the FDLR were directly coordinated from Europe.

FDLR leader Ignace Murwanashyaka and his deputy Straton Musoni were arrested by German authorities on November 17 on suspicion of crimes against humanity and war crimes committed in eastern Congo.

Two NGOs based in Spain are also named in the report as dealing with the FDLR.

This is not the first U.N. report linking the FDLR, and other armed groups operating in eastern Congo, with illicit trade of minerals with international companies.

While the international community continues to spend hundreds of millions of dollars on peacekeeping and humanitarian missions in eastern Congo each year, the rebels committing the atrocities against the population in the region continue to be funded by individuals and companies based in the donor countries, operating freely and enjoying complete impunity.